1. Field
The subject matter disclosed herein relates to data communication systems. In particular, embodiments disclosed herein relate to processing data received from an optical transmission medium.
2. Information
Optical communication networks have been implemented to enable increased data rates in links providing point to point communication. For example, optical communication links are typically implemented in Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) and 10 Gigabit Ethernet systems. At a receiving end of such an optical communication link, a photodiode may generate a current in response an optical signal received from an optical transmission medium (e.g., fiber optical cabling). A transimpedance amplifier (TIA) typically converts the current generated by the photodiode into a voltage signal that is then processed. For example, the voltage signal may be processed by clock and data recovery circuitry to recover data transmitted in the optical signal.
A TIA typically comprises a feedback circuit to remove a DC component of an input signal. A low pass filter (LPF) typically receives an output signal from the TIA to isolate the DC component. A DC removal circuit may then remove all or a portion of the DC component from the input signal based upon the DC component isolated from the output signal.
An LPF in an electronic device typically comprises an off-chip capacitor that may be coupled to one or more circuit elements in the electronic device by an external circuit bonding pad. When coupled to the one or more circuit bonding pads, the capacitor may be coupled to the one or more circuit elements through one or more conductive portions formed in the electronic device (e.g., as part of a circuit layout for a semiconductor device). At high frequency operation, the conductive portions may introduce a parasitic impedance resulting from a parasitic resistance and/or a parasitic inductance.
The parasitic resistance of a conductive portion may be reduced by, for example, increasing the cross-sectional area or width of the conductive portion (i.e., with reference to the direction of current between the off-chip capacitor and circuit elements in the electronic device). For a given conductive material (e.g., copper) increasing the cross-sectional area or width may lower the parasitic resistance proportionally. Decreases in parasitic inductance may also result from increasing the cross-sectional area or width. However, at a given operating frequency and conductor cross-sectional area or width, saturation may prevent significant further decreases in parasitic inductance from further increases in cross-sectional area or width.